The present invention is directed to a printing unit which includes at least three rotating bodies. These are a forme cylinder, a satellite cylinder and an inking roller.
A four-cylinder printing unit is known from DE 196 03 663 A1. Two transfer cylinders which cooperate with each other are fixedly coupled to each other and can be selectively driven by the drive mechanism of one or of both associated forme cylinders, or via a transverse shaft which can be connected to the motors. In one mode of operation, one of the forme cylinders can be stopped for a plate change. The associated transfer cylinder continues to run synchronously with the second forme cylinder.
A five-cylinder printing unit, described in DE 197 32 330 A1, has a mode of operation wherein one of the forme cylinders can be stopped for a plate change. The associated transfer cylinder is either also stopped or is rotatable, together with the forme cylinder, independently of the remaining three cylinders.
EP 0 997 273 A2 discloses a mode of operation of a four- cylinder printing unit wherein a forme cylinder is moved away from the remaining cooperating cylinders. In one example, the moved- away forme cylinder can be rotated by a drive motor, and in another example, it can be rotated by an auxiliary motor.
The object of the present invention is directed to providing a printing unit.
In accordance with the invention, this object is attained by providing a printing unit with at least three rotating bodies that cooperate in pairs to form a print-on position. These include a satellite cylinder, a forme cylinder, which cooperates with the satellite cylinder in the print-on position, and at least one inking roller which cooperates with the forme cylinder in the print-on position. At least two of these three rotating bodies simultaneously have a set-up rotational speed that is different from a production rotational speed and from a zero rotational speed.
The advantages which can be obtained by the present invention reside, in particular, in that a large operational diversity and variability of a printing unit or a cylinder assembly is created.
For example, it is possible, in this way, to move cylinders or groups of cylinders independently of each other at different rotational speeds, or also in different directions of revolutions which may be required, for example, when drawing in a paper web, or in the course of independent inking or washing of rollers and cylinders. In particular, different actions when setting up at set-up rotational speeds, or operations at speeds different from the stop or zero rotational speed, or the production rotational speed for the individual cylinder types are therefore possible on cylinders or groups of cylinders next to each other and with a paper web running or stopped.
The simultaneous meeting of several different demands made on different components of a printing group or of a printing unit is particularly advantageous. For one, the different operational modes of the components contribute to time savings and therefore to a lowering of the production costs, and furthermore make possible the performance of various set-up operations with the paper web running at production speed or at a draw-in speed. A flying plate change for single or doubled-sided imprint operations is possible. For example, in advantageous operational states, a printing forme is changed or pre-inked, while washing, pre-inking or also a change of the dressing takes place at the associated steel cylinder.
In particular, in connection with printing units which have a counter-pressure cylinder which is embodied as a steel cylinder, for example, various options for setting-up the cylinders without mutual interference arise while the paper web, for example, is drawn in at draw-in speed during a production start. Together with the modes of operation, or operational states in accordance with the present invention, these printing units permit the guidance of the paper web at draw-in speed while set-up work can take place at a forme cylinder.
For reasons of flexibility and of savings of time, as well as of waste, the operational states, in accordance with the present invention are of great importance in the course of cylinder set-up or fitting prior to start-up, or at the end of the printing operation. For example, the forme cylinder and the inking roller can simultaneously pass through-different set-up programs.
The independent operation of the rollers for ink application, which are assigned to the forme cylinders, is also advantageous. For example, washing or pre-inking of these rollers can take place regardless of the rotational speed and of the direction of rotation and while the forme cylinder also passes through a set-up program.